Sidelooker LED Smoke Detector Height Reduction
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Solution Overview
Problem
Existing open scattered light smoke detectors have a large overall height and are vulnerable to mechanical and environmental influences, with a significant loss of measuring light due to the backward scattered light arrangement.
Innovation Solution
The light transmitter and receiver are arranged such that a large part of the directional beam path runs parallel to the circuit carrier's outside, reducing the overall height and protecting the optically active surfaces, with a 'side looker' LED emitting light parallel to the circuit carrier and a shielded light receiver detecting scattered light through an optical window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the light transmitter and receiver are arranged in a backward scattered light arrangement, then the overall height is reduced, but the measuring light is significantly lost and the optically active surfaces are vulnerable to mechanical and environmental influences
Solution Approach 1:
The light beam path is redirected to run parallel to the circuit carrier instead of perpendicular, changing the spatial dimension of light propagation. This allows the light transmitter and receiver to be positioned on the same plane, reducing overall height while maintaining optical path length and preventing light loss.
Solution Approach 2:
The circuit carrier serves as an intermediary structure that provides both mechanical support and optical guidance. The light beam travels along the surface of the circuit carrier, using it as a mediator to achieve both compact positioning and protected optical paths.
2Length of stationary object
If the light transmitter and receiver are arranged in a backward scattered light arrangement, then the overall height is reduced, but the optically active surfaces are unprotected against mechanical and environmental influences
Solution Approach 1:
A transparent protective cover is introduced as a thin film structure that covers the circuit carrier and optically active surfaces. This cover protects against mechanical and environmental influences while allowing light to pass through, solving the contradiction between compact design and protection.
Solution Approach 2:
The light transmitter and receiver are nested on the circuit carrier plane, with the protective cover enclosing them. This nested arrangement allows the optically active surfaces to be positioned compactly while being protected by the surrounding cover structure.
3Device complexity
If the light beam path runs perpendicular to the circuit carrier, then the optical alignment is simple, but the overall height increases and light detection efficiency decreases
Solution Approach 1:
The optical alignment is transitioned from a perpendicular (vertical) arrangement to a parallel (lateral) arrangement along the circuit carrier surface. This dimensional change reduces height while maintaining alignment simplicity through the planar geometry of the circuit carrier.
4Ease of manufacture
If the light transmitter uses a conventional LED, then the light emission is omnidirectional, but the beam directionality is poor
Solution Approach 1:
A beam shaping element is introduced as an intermediary component between the conventional LED and the detection area. This element maintains the ease of using standard LEDs while providing the necessary beam directionality and parallel propagation along the circuit carrier surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces the overall height of the smoke detector, enhances light detection efficiency, and provides better protection against mechanical and environmental influences while maintaining reliable light distribution for accurate smoke detection.
Implementation Method 1
The light transmitter (4, 41, 42) is designed to emit a light beam (L) with a directional beam (RS)
Implementation Method 2
The light transmitter and the light receiver (5, 51-53) are arranged in a scattered light arrangement with a scattered light volume (M, M1)
Implementation Method 3
a shielded light receiver detecting scattered light through an optical window
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
An open-type scattered light smoke includes a housing shell supporting a circuit substrate having at least one light emitter and one light receiver arranged thereon. The light emitter and the light receiver are arranged in a scattered light array having a scattered light volume located in the open air outside the smoke detector. The light emitter emits a light beam having a direction pay, with part of the path traveled by the directional ray between the light emitter and the scattered light volume running parallel to an outer face of the circuit substrate facing away from the housing shell. The light emitter may be an LED housed in a sidelooker package and the light receiver may be a photodiode housed in a reverse-gullwing package. A sensor surface of the photodiode is aligned opposite the scattered light volume through an opening in the circuit substrate that provides mechanical protection.